Failed NOx Help? - Page 2 - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


1992-1999 Series I L27 (1992-1994 SE,SLE, SSE) & Series II L36 (1995-1999 SE, SSE, SLE) and common problems for the Series I and II L67 (all supercharged models 92-99) Including Olds 88's, Olds LSS's and Buick Lesabres Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

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Old 08-27-2004, 10:11 PM   #11
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Don't even need the key in the ignition...hope it works out for you
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Old 08-28-2004, 01:00 PM   #12
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I don't think the catalytic converter is there for NOx. It'* purpose is to reduce hydrocarbons, not NOx.
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Old 08-28-2004, 02:31 PM   #13
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Quote:
Originally Posted by fuddyduddy121
I don't think the catalytic converter is there for NOx. It'* purpose is to reduce hydrocarbons, not NOx.
"Catalytic converters can either be an oxidation or three-way type. Oxidation catalysts convert carbon monoxide (CO) and hydrocarbons (HC) to carbon dioxide (CO2) and water, but have little effect on nitrogen oxides (NOx) and particulate matter. Three-way catalysts operate in a closed-loop system together with a lambda, or oxygen, sensor to regulate the air/fuel ratio on gasoline engines. The catalyst can then at the same time oxidize CO and HC to CO2 and water while reducing NOx to nitrogen.

Most cars today are equipped with a three-way catalytic converter. The term Three-way refers to the three emissions it helps to reduce, carbon monoxide, hydrocarbons or volatile organic compounds (VOCs) and NOx molecules."

http://autorepair.about.com/cs/gener.../aa080401a.htm

The only question is how "today" is a '93? Thats the thing I hate about some manuals. Well sheit was this written in 1950?! Or was it in 2004 and they're being literal with 'today'. Do you know if which one we use? I'm kind of curious now, this was news to me.
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Old 08-28-2004, 05:46 PM   #14
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I have a hard time believing the NOx reduction in a catalytic converter is very effective, effective NOx reduction usually only occurs at the source with lower combustion temperatures or lower residence time.

For effective NOx reduction in an exhaust stream using catalytic reduction, you really need some time of ammonia or urea injection. I still have difficulty blaming the cat for high NOx.
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Old 08-28-2004, 06:10 PM   #15
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Yeah I doubt the cat would be his problem as I would expect to see everything high when failed. I'm not sure how much the cat reduces nox but aparently the chemical responsible for it is called Rhodium. More info avail: http://www.autoshop101.com/forms/h64.pdf

Haven't read it all but looks very informative.
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Old 08-29-2004, 03:54 AM   #16
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not sure if your EGR valve is digital, neg. back pressure or what but if its neg. back pressure (has the solenoid which hooks via vac. line to the bulby- gold thing) you should also check to see if the valve itself opens or not.. to make it open, just unplug one of the vacuum lines at the Solenoid ( i remember it being the vacuum hose that does NOT go from solenoid to valve) and just plug it with your finger and that makes the valve open and thus the car starts sputtering and coming to a stall... if your valve is locked shut it shouldn't open at all..

on mine, the valve was ok but the solenoid was bad :/
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Old 09-08-2004, 10:16 AM   #17
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Just want to finish up the thread so when people search they see what I did.
After replacing the PCV valve, cause in NJ they want a reciept showing you actually did something to car, I drove home from work for like half an hour and went through again, just letting it get hot, what a diference it made

Standard 853, Failed without car warm 1115, With fully warmed car, 91! Pass

HC went up 2pnts to 6, but was well below the 114 standard. Thanks for all the help. Now I can change the O2 sensor when I get around to getting the socket.
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